Fast moving steering mirrors (FSM) (also known as “beam steering mirrors”) are commonly used in high-performance electro-optical sensors or laser systems for pointing laser beams or stabilizing the line of sight of an optical sensor. In many applications the FSM is large enough (e.g., about 2 inch to about 20 inch aperture mirror) that motion of the mirror must be implemented in a way that its exported reaction loads (e.g., “kickback” torque and/or force due to acceleration of the mirror) are compensated for by a mass moving in the opposite direction of the mirror. To be effective, the reaction mass must be driven in such a way that the phase error with the mirror is extremely low to ensure that the exported load is minimized. This is generally accomplished either by driving the reaction mass and the mirror directly against one another so that the reaction mass passively/inherently compensates for the mirror motion or by actively driving the reaction mass with a dedicated separate set of actuators and tilt position sensors.
Reference will now be made to the exemplary embodiments illustrated, and specific language will be used herein to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended.